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In: fish consumption, Jim Hurley, mercury, methylmercury, nature

Reducing mercury pollution to lakes can lower methylmercury contamination in fish within just a few years according to research reported today in the online version of the journal Nature. The findings suggest efforts to control mercury emissions can reduce the risk of human exposure through fish consumption.

Mercury released because of human activity can find its way into aquatic ecosystems, where it is converted into methylmercury, a potent neurotoxin that accumulates in fish and poses a health threat to humans. There is limited understanding of the effectiveness of controls on mercury emissions in removing methylmercury from the food chain.

Two people in boat.

Researchers in the Experimental Lakes Area of Canada adding mercury isotopes to study lake. Contributed photo.

A 15-year study on the effects of mercury control efforts on the recovery of fish contamination was conducted on a remote, undisturbed Canadian lake and its watershed. Wisconsin Sea Grant Director Jim Hurley was part of the research team that also included scientists from binational regulatory agencies and other academic institutions in the U.S. and Canada.

“This study shows the value of long-term multi-disciplinary, consistent research. We were able to observe the impacts of both an increase and decrease in contaminant loading over several years. Both showed rapid responses in the chemistry and biology of the lake and its watershed,” Hurley said.

Close-up of two men pouring liquid from one jug to another jug.

Jim Hurley (left) and Todd Kuiken, Canada Department of Fisheries and Oceans, homogenize the mercury isotope solution to ensure the carboys on each boat have the same concentration. Photo: Chris Babiarz

This whole-ecosystem experiment for seven years supplied specific isotopes of mercury to the ecosystem. During this period, the researchers recorded an increase in the uptake of this isotopically labelled mercury as methylmercury in the fish. Methylmercury concentrations increased by 45–57% in invertebrates (plankton, for example) and small fish (such as yellow perch), and by more than 40% in large fish, such as pike and whitefish.

Then, mercury additions ceased and the effects on the food chain were observed for eight years. Labelled methylmercury quickly diminished in the smaller fish, with concentrations dropping by at least 85% by the end of the study period. This triggered a subsequent reduction of labelled methylmercury in the larger fish, with concentrations declining by 76% in pike and 38% in whitefish.

The rapid reductions in methylmercury contamination observed in these experiments demonstrates the potential for mercury emission controls to improve the safety of fish for human consumption, the authors concluded. 

 

The post Study in Nature shows reduction of mercury pollution in waterways reaps relatively quick benefit first appeared on Wisconsin Sea Grant.

Original Article

News Releases | Wisconsin Sea Grant

News Releases | Wisconsin Sea Grant

https://www.seagrant.wisc.edu/news/study-in-nature-shows-reduction-of-mercury-pollution-in-waterways-reaps-relatively-quick-benefit/?utm_source=rss&utm_medium=rss&utm_campaign=study-in-nature-shows-reduction-of-mercury-pollution-in-waterways-reaps-relatively-quick-benefit

Moira Harrington

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In: Environmental Science and Technology Journal, fish consumption advisories, mercury, methylmercury, Ryan Lepak

Methylmercury uptake rate in phytoplankton is among the highest recorded   

Sept. 22, 2021
By Moira Harrington

A recently published study in the journal of the American Chemical Society, Environmental Science and Technology, found that while Great Lakes waters harbor low methylmercury concentrations, the rates of methylmercury transfer to phytoplankton are extremely high, higher than rates observed in open oceans. Phytoplankton are the smallest organisms in an aquatic food web.

Researchers, including a UW-Madison-supported postdoctoral scientist, say this is important because the bioaccumulation of methylmercury into phytoplankton sets the baseline for methylmercury levels in fish.

Methylmercury is highly toxic and is the form most encountered by people. This is generally through eating fish and shellfish, which is why advisory consumption guidelines are issued, particularly targeted toward pregnant women and young children. However, monitoring fish and shellfish varieties—some have higher levels of methylmercury—and consumption frequency, people can still enjoy the health benefits of omega-3 fatty acids found in the food.

From 2010 to 2018, the U.S. Geological Survey Mercury Research Lab in Madison, Wisconsin, teamed up with the U.S. EPA and its research vessel the Lake Guardian to monitor inorganic and methylmercury dynamics in the five Great Lakes. This was done through a combination of vertically, seasonally and spatially comprehensive water quality measurements and analysis of seston collections, which is the suspended particle mass in the lakes made up of plankton, bacteria, bugs and detritus.

Ryan Lepak, a postdoctoral scientist (Ph.D. UW-Madison, 2018) through the University of Wisconsin Water Resources Institute and its sister organization, Sea Grant and stationed at the U.S. EPA Mid-Continent Ecology Division in Duluth, Minnesota, said, “Ultimately, the study concluded the very low concentrations of dissolved organic carbon, the substrate which competes with phytoplankton for methylmercury but also can serve as a source of sustenance, in these lakes likely create a scenario where methylmercury transfer to phytoplankton is facilitated. The planktonic methylmercury levels are quite low, but exceedingly higher than we’d expect considering the extremely low methylmercury levels in the waters in which they reside.”

Ryan Lepak aboard the U.S. EPA RV Lake Guardian sampling for methylmercury. Contributed photo.

Lepak continued by explaining the transfer of methylmercury up the lower food web, from phytoplankton to herbivorous zooplankton and then to omnivorous zooplankton, was not statistically different. Finally, he and the team tested whether water-mercury concentrations have declined over the study period and determined that without more routine continuous monitoring, trends could not be identified because unresolved sources of variability masked data trends.

“The conditions that make the Great Lakes highly susceptible to methylmercury bioaccumulation are common to the world’s great lakes,” Lepak said. “These global water bodies should serve as excellent sentinels to track the impacts mercury reductions at local, regional and global scales have on biota. This paper’s important finding could aid those planning global mercury monitoring networks aimed at tracking mercury reductions due to actions resulting from the Minamata Convention on Mercury, a multilateral environmental agreement the U.S. signed in 2013 and which would reduce global mercury pollution.”

 

The post Methylmercury water concentrations low, but Great Lakes fish consumption advisories persist—new research documents one probable culprit first appeared on WRI.

Original Article

News Release | WRI

News Release | WRI

https://www.wri.wisc.edu/news/methylmercury-water-concentrations-low-but-great-lakes-fish-consumption-advisories-persist-new-research-documents-one-probable-culprit/

Moira Harrington

On:
In: Environmental Science and Technology, fish consumption advisory, mercury, methylmercury, phytoplankton, Ryan Lepak

Methylmercury uptake rate in phytoplankton is among the highest recorded  

 A recently published study in the journal of the American Chemical Society, Environmental Science and Technology, found that while Great Lakes waters harbor low methylmercury concentrations, the rates of methylmercury transfer to phytoplankton are extremely high, higher than rates observed in open oceans. Phytoplankton are the smallest organisms in an aquatic food web.

Researchers, including a UW-Madison-supported postdoctoral scientist, say this is important because the bioaccumulation of methylmercury into phytoplankton sets the baseline for methylmercury levels in fish. 

Methylmercury is highly toxic and is the form most encountered by people. This is generally through eating fish and shellfish, which is why advisory consumption guidelines are issued, particularly targeted toward pregnant women and young children. However, monitoring fish and shellfish varieties—some have higher levels of methylmercury—and consumption frequency, people can still enjoy the health benefits of omega-3 fatty acids found in the food.

From 2010 to 2018, the U.S. Geological Survey Mercury Research Lab in Madison, Wisconsin, teamed up with the U.S. EPA and its research vessel the Lake Guardian to monitor inorganic and methylmercury dynamics in the five Great Lakes. This was done through a combination of vertically, seasonally and spatially comprehensive water quality measurements and analysis of seston collections, which is the suspended particle mass in the lakes made up of plankton, bacteria, bugs and detritus.

Ryan Lepak, a postdoctoral scientist (Ph.D. UW-Madison, 2018) through Sea Grant and its sister organization the University of Wisconsin Water Resources Institure and stationed at the U.S. EPA Mid-Continent Ecology Division in Duluth, Minnesota, said, “Ultimately, the study concluded the very low concentrations of dissolved organic carbon, the substrate which competes with phytoplankton for methylmercury but also can serve as a source of sustenance, in these lakes likely create a scenario where methylmercury transfer to phytoplankton is facilitated. The planktonic methylmercury levels are quite low, but exceedingly higher than we’d expect considering the extremely low methylmercury levels in the waters in which they reside.”

Ryan Lepak aboard the U.S. EPA RV Lake Guardian sampling Great Lakes waters for methylmercury. Contributed photo.

 Lepak continued by explaining the transfer of methylmercury up the lower food web, from phytoplankton to herbivorous zooplankton and then to omnivorous zooplankton, was not statistically different. Finally, he and the team tested whether water-mercury concentrations have declined over the study period and determined that without more routine continuous monitoring, trends could not be identified because unresolved sources of variability masked data trends.

“The conditions that make the Great Lakes highly susceptible to methylmercury bioaccumulation are common to the world’s great lakes,” Lepak said. “These global water bodies should serve as excellent sentinels to track the impacts mercury reductions at local, regional and global scales have on biota. This paper’s important finding could aid those planning global mercury monitoring networks aimed at tracking mercury reductions due to actions resulting from the Minamata Convention on Mercury, a multilateral environmental agreement the U.S. signed in 2013 and which would reduce global mercury pollution.”

 

The post Methylmercury water concentrations low, but Great Lakes fish consumption advisories persist—new research documents one probable culprit first appeared on Wisconsin Sea Grant.

Original Article

News Releases | Wisconsin Sea Grant

News Releases | Wisconsin Sea Grant

https://www.seagrant.wisc.edu/news/methylmercury-water-concentrations-low-but-great-lakes-fish-consumption-advisories-persist-new-research-documents-one-probable-culprit/?utm_source=rss&utm_medium=rss&utm_campaign=methylmercury-water-concentrations-low-but-great-lakes-fish-consumption-advisories-persist-new-research-documents-one-probable-culprit

Moira Harrington